肢体骨肉瘤新辅助化疗前后髓腔MRI T1像信号的变化

目的：探讨肢体骨肉瘤新辅助化疗前后髓腔MRIT1像上信号的变化。方法回顾研究58例肢体骨肉瘤，将新辅助化疗前后髓腔的MRI T1像进行对比，记录化疗前患者的MRI T1像肿瘤与正常髓腔是否有清晰边界，化疗后分界是否仍清晰，不清晰出现的比例及信号变化。部分患者进行了双侧肢体 MRI检查，对比双侧MRI信号的异同。获得瘤段截除标本后，对化疗后出现信号改变的部位进行病理取材，研究这种信号改变的组织学构成。结果髓腔MRIT1信号形态可分为清晰、连续弥漫、间断岛状、间断弥漫4种，58例患者入院MRI上均为清晰的髓腔分界。化疗后MRI边界清晰22例，占37.9%，36例为化疗前MRI清晰而化疗后变为不清晰，占62.1%。其中连续弥漫20例，占34.5%；间断岛状4例，占6.9%；间断弥漫12例，占20.7%。9例化疗后 MRI 可显示双侧股骨，健侧股骨髓腔内也出现了与患侧股骨类似的斑片状弥漫信号。对33例MRIT1加权像上显示异常的区域进行取材，组织学显示为增生的骨髓造血细胞，无肿瘤细胞。结论新辅助化疗前后MRI T1像上显示的骨肉瘤髓内异常信号范围可发生变化，部分患者在新辅助化疗后出现瘤旁异常信号，对于这些肿瘤外的、形态上呈岛状及弥漫斑片状的异常信号，如在 MRI T1像上较脂肪信号低，较骨骼肌信号高，临床上要考虑到有可能发生了骨髓逆转换，是骨髓的正常变化，不能将这种增生骨髓误认为肿瘤的进展而造成截骨长度的增加。

Signal changes of MRI T1-weighted images of the medullary cavity before and after the neoadjuvant chemotherapy for extremity osteosarcoma

Objective To investigate the signal changes of MRI T1-weighted images of the medullary cavity before and after the neoadjuvant chemotherapy for extremity osteosarcoma.Methods The clinical data of 58 cases of extremity osteosarcoma were retrospectively studied. The MRI T1-weighted images of the medullary cavity before and after the neoadjuvant chemotherapy were compared. It was recorded whether the margin between the tumor and the normal medullary cavity was clear before and after the chemotherapy, the occurrence of blurring and the signal changes. The MRI examination of bilateral limbs was performed on some patients. The signal differences between the 2 sides were compared. After the tumor-bearing segment was resected, the specimen of abnormal signals after the chemotherapy was analyzed pathologically. The histological structures of such signals were studied.Results The signal aspects of MRI T1-weighted images of the medullary cavity could be classiifed into 4 kinds, which were clear, continuous diffuse, discontinuous island-like and discontinuous diffuse respectively. Before the chemotherapy, the clear margin could be observed in all 58 patients. After the chemotherapy, the clear margin could be observed in 22 patients （ 37.9% ）. It occurred to 36 patients （ 62.1% ） that signals changed from clear to unclear after the chemotherapy. There were 20 continuous diffuse cases （ 34.5% ）, 4 discontinuous island-like cases （ 6.9% ） and 12 discontinuous diffuse cases （ 20.7% ）. The MRI showed bilateral femurs in 9 cases after the chemotherapy. The patchy and diffuse signals in the medullary cavity of the normal femur were similar to those of the affected femur. The specimen was taken based on the MRI T1-weighted images of 33 cases which showed abnormal signals. The histological studies showed no tumor cells but the proliferation of hematopoietic cells.Conclusions The range of abnormal signals in the medullary cavity with osteosarcoma may change based on the MRI T1-weighted images before and after the n